US20030114799A1 - Safety injection device - Google Patents

Abstract

An injection device for intramuscular or subcutaneous injection of solid or semi-solid medicaments is disclosed. The device includes main body member having a needle attached thereto. A protective sleeve covers the needle and retracts into the main body member when the device is pressed against the skin of a patient. A plunger with an attached rod maintains the medicament in the patient as the needle is withdrawn.

Description

• The present invention relates to injection devices and, in particular, to a device for the intramuscular or subcutaneous injection of a pharmaceutically active compound.[0001]
• The parenteral introduction of pharmaceutically active compounds is preferred over oral dosage in many applications. For example, when the drug to be administered would partially or totally degrade in the gastrointestinal tract, parenteral administration is preferred. Similarly, where there is need for rapid response in emergency cases, parenteral administration is preferred over oral administration.[0002]
• Thus, while parenteral administration is desirable in many applications, as it is currently practiced it has substantial drawbacks. Probably the biggest drawback is the discomfort which it causes the patient to whom the drug is being administered. Parenteral preparations generally contain a large volume of liquid in which the drug is suspended or dissolved. Ratios of active ingredient to carrier commonly run from 1:100 to 1:1000. When the active ingredient is poorly soluble or difficult to suspend in the carrier, or when the active ingredient has to be administered at high doses, or in both instances, a fairly large volume of liquid must be injected. Both the size of the needle and the volume of liquid being injected cause parenteral administration to be more or less painful, and at least disagreeable, for most people. Furthermore, depending on its nature, the carrier itself may be a cause of pain.[0003]
• A further disadvantage to administration of drugs in a liquid carrier is that the drugs are frequently not stable in the liquid. Therefore, the liquid and drug must be mixed substantially contemporaneously with injection. This can be of substantial disadvantage where, for example, many hundreds of people must be treated over a course of days in order to stem an epidemic.[0004]
• Drugs in solid form rather than liquid form have been used for prolonged or controlled release formulations. When the formulation is not a microstructure or a powder that can be injected in suspension form, with a liquid and a standard syringe, the formulation is usually an implant or a rod which can be injected directly via a trocar, see for example European Patent Application Publication No. 0292936. However, trocars and the device as set forth in the cited European Patent have some disadvantages. When the formulation is a prolonged or controlled formulation, the formulation must contain the daily dose of drug multiplied by the number of days of activity of the drug and the amount of carrier necessary to control the rate of delivery of that drug. Thus this formulation, which is in the needle, requires a needle significantly larger than ordinary needles used with syringes and this results in a painful injection.[0005]
• The applicant has now discovered a comparatively inexpensive device for the ready administration of solid or substantially solid drugs by the parenteral route wherein the drugs are intended to be immediately assimilated by the body.[0006]
• Because the quantity of drug is just the amount needed for an immediate effect and because there is no need for carriers to control function, the needle can be as small as ordinary needles. The drug is stable because it is in solid form and, thus, no contemporaneous mixing is needed. The injection is substantially painless because the needle size for the injected volume is dramatically reduced as compared to the size needed for liquid injection. The risk of contamination can be reduced because there is no pre-manipulation of the injectable formulation before making the injection. A seal can be fitted on the tic of the injection member so that there is complete sterility until injection into the skin.[0007]
• Finally, because there is no volume of liquid to inject, the procedure is simplified.[0008]
• The applicants herein filed a co-pending application Ser. No. ______ on Sep. 12, 1994 entitled NEEDLE-LESS PARENTERAL INTRODUCTION DEVICE, the teaching of which is hereby incorporated by reference. The device in this co-pending application comprises a housing and a plunger. The plunger pushes a solid medicament out of a bore in the housing and directly into the patient. This device works very well for drugs which can be made structurally strong enough to penetrate the skin. However, it has been found that there are some drugs which cannot be made structurally strong enough. While such drugs could be combined with a structurally strong carrier, there are instances where the use of such carrier is undesirable.[0009]
• In accordance with the present invention the applicants have developed a device similar to the NEEDLE-LESS PARENTERAL INTRODUCTION DEVICE except that in the instant case the device includes a needle. Unlike past devices, however, the device of the present invention has a needle which is never exposed to the outside elements. Thus it can never pick up airborne contaminants, nor can it inadvertently scratch someone, such as a hospital worker. This aspect is especially important for treatment of mentally unstable patients.[0010]
• These and other aspects of the present invention may be more fully understood with respect to the drawings wherein:[0011]
• FIG. 1 shows the device at rest;[0012]
• FIG. 2 shows the device with the needle injected into the patient;[0013]
• FIG. 3 shows the needle being withdrawn with the medicament remaining in the patient;[0014]
• FIG. 4 shows complete withdrawal of the needle from the patient; and[0015]
• FIG. 5 shows a cross-section through line[0016]5-5 of FIG. 1.
• Referring first to FIG. 1 there is shown main body member[0017]10a, lob which is attached toneedle12 through coupling means14. Arod16 is guided intoneedle12 andabuts medicament20 which is positioned inneedle12. Asleeve22 surroundsneedle12 so thatneedle12 is not exposed until used.Sleeve22 is provided with one or more slots40 (see FIG. 5) along its length so that main body members10aand lob can be joined by radially extending connectingmembers42. A seal24 covers the opening23 and theslots40 ofsleeve22 in order to maintain the sterility ofneedle12 andmedicament20. The seal is preferably of easily friable material such as wax.Rod16 includes abulb26 which serves as a stop for travel of therod16.Main body member10 has aflange28 to assist in removal of the device after injection.Rod16 is attached to aplunger29 which has atop thumb flange18. Aguide30 is attached toplunger29 and is positioned inmain body member10 to guideplunger29 androd16.
• FIG. 2 shows the device of FIG. 1 wherein[0018]needle12 has penetrated theskin32 of the person being treated. As shown,needle12 has penetrated through theskin32 into thesubcutaneous layer34. As the device of FIG. 1 is pressed against theskin32,sleeve22 is retracted intomain body member10 by the force of pressure against theskin32.
• At this point, and as shown in FIG. 3,[0019]main body member10 is moved in an upward direction by exerting finger pressure against the lower part offlange28 while simultaneously exerting opposing pressure with the thumb onflange18 ofplunger29. This relative movement of theplunger29 and themain body member10 causes theneedle12 to retract intosleeve22 thus leavingmedicament20 in thesubcutaneous layer34 of the patient.
• FIG. 4 shows the[0020]needle12 fully withdrawn intosleeve22 and withmedicament20 remaining in thesubcutaneous layer34 of the patient. As can also be seen in FIG. 4, the upper portion15aofrod16 has been pushed into abore27 inplunger29 by the action of coupling means14 againstbulb26 ofrod16.
• FIG. 5 is a cross-sectional view of FIG. 1 at[0021]5-5. FIG. 5shows slots40 insleeve22. Radially extending connectingmembers42 extend through theslots40 to join main body member10awith main body member lob.
• As will be appreciated from the foregoing drawings and description, the only time that the needle came out of its protective sleeve was when it was already abutted against the patient's skin. At no time is the needle ever exposed to the air where it could become contaminated or where it might inadvertently scratch someone.[0022]
• Turning now to the[0023]medicament20, it is preferred that it be solid or semi-solid. It is preferred that the device of the present invention be used with a medicament that is not strong enough to penetrate the skin; however, in some applications, it is acceptable for the medicament to have such strength. The amount of carrier, if present, should be as small as possible. As a general rule, the amount of active ingredient in themedicament20 is at least 20% and is preferably above 50%. With suitable medicaments which will hold a shape, the amount of medicament can be up to 100%. The medicament may be prepared by conventional techniques such as compression, thermofusion or extrusion. Compression suitably consists of a tabletting process in which a microtablet is formed. The diameter of themedicament20 may be up to 2 mm but is preferably from about 0.25 to about 0.5 mm in diameter and about 1 to about 3 cm in length. The diameter of therod16 is preferably about the same diameter as the diameter of themedicament20. The inside diameter of theneedle12 is preferably just slightly larger than the diameter of the medicament. It is preferred that theneedle12 androd16 be metallic, notably stainless steel; the balance of the components can be relatively inexpensive plastic materials.
• It will be understood that the claims are intended to cover all changes and modifications of the preferred embodiments of the invention herein chosen for the purpose of illustration which do not constitute a departure from the spirit and scope of the invention.[0024]

Claims (6)

What is claimed is:

1. In an injection device for injecting a solid or semi-solid medicament parenterally in a mammal, said device including a main body member, a needle affixed to said main body member, a rod within said needle, said rod extending through said main body member and said rod being affixed to a plunger, a sleeve which covers said needle, said sleeve being slidably positioned in said main body member, and wherein when said device is pressed against a mammal said sleeve retracts into said main body member thereby allowing said needle to penetrate said mammal and said plunger and rod being operative to maintain a medicament through said needle in said mammal as the needle is being withdrawn from said mammal.

2. The device ofclaim 1 wherein said rod includes a bulb which functions as a stop.

3. The device ofclaim 1 wherein said plunger includes a flange.

4. The device ofclaim 1 wherein said main body member includes a flange.

5. The device ofclaim 1 wherein said sleeve includes a seal operative to maintain the sterility of the needle.

6. The device ofclaim 1 wherein said needle contains a medicament.

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